Hey all,

Quick rundown. I have a 2013 Mini Cooper S i just recently installed a new RPM turbo on along with a stage 3 RPM tune and TurboSmart BOV.

When i attempt to pull in traffic to pass the car goes into limp mode and throws:

2C90 - thrust air circulation valve locked closed
36c9 - DME internal error: plausibilzation of fuel mass too low.

I was able to get a data log today of 3rd and 4th gear pulls and 4th gear pull was where the codes popped up. According to the tuners revew of the data logs:

"Not very good news I'm afraid. Boost is peaking at 2170 millibar absolute manifold pressure (Ladedruck). Subtract 1000 mb for atmospheric pressure and its 1.17 bar or just under 17 psi. Wastegate is also maxed out at ~85% duty cycle. On a PWM controlled solenoid pretty much anything after 80% to 83% is wide open. So, you are not getting anywhere near the boost you should be getting.Fuel and timing are within expected norms for the boost level it's at."

Are there any common things to look at here that could cause this issue? Codes came on as well with the new turbos "stock" BOV and are still occuring with the new turbosmart valve.

i will note the hot side turbo pipe by the coolant tank is a bit soft as is the the turbo actuator small thin hose. I read up a bit that the "boost solenoid" under the intake that the thin actuator hose connects to could be another point of failure but just wanted to see thoughts.

thanks in advance!

 

Well, I've heard RPM stage 3 and up tunes aren't always the most trouble free....

Code 2C90 seems to be tied to the diverter valve not opening when expected. The only service plan for that code is to replace the diverter valve. Maybe you just need to try a new OEM valve?

Code 36C9 seems to be tied to the fuel rail pressure sensor, and the reading it is sending to the DME is lower than expected. Maybe RPM tweaked the sensor targets, and they are higher than your fuel system can produce? Or, its not unheard of that the rail sensor needs to be replaced.

Have you put these codes in front of your tuner contact? (I am assuming Mario?) What is the tuner response to those codes?

 

@njaremka the tuner mentioned the fuel rail pressure sensor but is that really something that would be fine pretty much the reat of the time except under higher rpm, his comment on that is below:

"Could also be the rail pressure sensor is starting to go out. During spikes you're showing over 16 MPa (2300 psi) of rail pressure and there's no reason to tune it that high"

he also advised the below based off of the readings from the data log:

"This tells me there is probably either a large boost leak, the pneumatic control valve is not working properly, the vacuum lines are collapsing or there is a problem with the turbo itself."

As mentioned, even with the "stock" piersburg diverter valve that came with the RPM turbo, these lights were still coming on.

 

I entered the codes on this site for help with diagnostics.
https://bmwfault.codes/

2C90 implies the diverter valve is sticking closed. I assume the DME comes to that determination when letting off the throttle pedal and boost doesn't release as fast as expected. Again, that's my assumption based on that code. The code is stored immediately upon condition. The only service plan for that code is to replace the diverter valve.

36C9 is tied directly to the fuel rail pressure sensor and the DME. The service plan involves checking the wiring between the DME and the rail pressure sensor, replacing the DME, or replacing the pressure sensor.

Neither of those codes are related to the vacuum system or the pressure converter, so those comments mean nothing. If the wastegate wasn't working correctly, there are different codes that would come up. If you had a large boost leak, you would know it, and it wouldn't necessarily throw a code. I had my intercooler outlet pipe blow completely off once. I heard a loud "Pop" and lost all boost and power. And, no codes.


I'll say it again, and I hope its not true in this case, but RPM stage 3+ tunes haven't always been trouble free....

 

The new pressure sensor and vacuum hoses are coming tomorrow. New turbo piping coming today.

That pressure sensor is in a tough spot so intake had to come off. Works anyways as it gives me better access to the small vacuum lines that im replacing.

I will update once everything back together. Fingers crossed

 

@njaremka well...i can proudly say it's fixed!

Replacred the small vacuum lines that go to the turbo actuator and vaccum pump back to the boost solenoid and vaccum box.

-Hot side turbo pipe (got rid of the old one with the muffler in it)

-the fuel rail pressure sensor

i don't believe the fuel rail pressure sensor was the issue. I think what was ultimately happening was under load those small lines that operate the actuator were collapsing and causing the eratic readings of boost to the fuel rail pressure sensor causing the code.

wow does this thing ZIP now. Super stoked to be back on the road!